The current invention is related to a method for manufacturing a spectacle lens and a spectacle lens.
It is well known in the art that spectacle lenses can be used for the correction of visual impairment. Ideally, a spectacle lens is not only manufactured to fit the individual needs of a spectacle wearer best possible but also at minimum cost. Spectacle lenses are described by the shapes of their back surface and their front surface. Typically, the visual impairment of a spectacle wearer is described by the so-called prescription that provides parameters for spherical power, astigmatic power and prismatic power to correct for the aberrations of the wearer's eye.
Different processes for manufacturing such spectacle lenses are known. For example, casting or molding processes are known and usually considered as the most cost-effective manufacturing processes. In a typical molding process, two mold halves are placed adjacently to create cavity having a desired geometry for the spectacle lens. Into that so-formed cavity, a polymerisable material, a thermosetting material or a thermoplastic material may be inserted to form the spectacle lens. Further, a granulate or pellets may be heated and processed via die casting or injection molding. In particular, such molding processes are advantageous in case no further surface processing steps are required afterwards, for example for polishing or grinding.
Further, typical surface machining methods are known which start off with lens blanks having neither their front surface nor their back surface in a desired geometrical shape. Alternatively, starting off with so-called semi-finished lens blanks is also known wherein either the front or the back surface already has a desired geometric shape and only the other unfinished surface is to be grinded and polished as required. During surfacing, i.e. grinding and polishing, not only rotationally symmetric shapes but also asymmetric and freeform surfaces can be formed. Hence, such processes are usually used when it is required to manufacture spectacle lenses for an individual wearer taking into account his/her individual parameters and desired usage of the spectacle lens. Hence, progressive lenses are usually manufactured in that way.
However, these processes also have certain drawbacks. For example, in particular when using semi-finished lens blanks, the manufacturer always has to keep a stock of a multitude of prototype lens blanks distinct in spherical power, astigmatic power, prismatic power and/or addition, wherein “addition” means the difference between a spherical power in the far or distance portion and the near portion of a progressive lens.
Further, such manufacturing processes usually require a relatively long time period since adequate manufacturing facilities are not present at every eyecare provider or spectacle shop. Hence, spectacle lenses are usually ordered directly at the manufacturer's sides or a large scale production unit. Spectacle lens manufacturing facilities produce the spectacle lenses with geometric shapes as desired and deliver them to the eyecare provider in a standard circular or elliptical shape. Then, in the spectacle shop or at the eyecare provider, this spectacle lens merely has to be adapted and fit to a specific frame.
Therefore, in the art, there was always a tendency to look for new manufacturing methods for spectacle lenses.
For example, document US 2011/0298877 A1 shows a print head for printing optical structures in a substrate comprising an injection device for ejecting at least one droplet of a printing ink towards the substrate and a curing device for curing the at least one deposited droplet, wherein the curing device comprises at least one UV-LED (Ultra Violet Light Emitting Diode).
Further, document EP 2 412 767 A1 shows a printing ink, a use of printing ink, an article and a method for manufacturing an article. The document relates to a printing ink for printing optical structures on a substrate by means of an ink jet printer, wherein the printing ink is at least partially transparent for optical light in a range between 380 and 780 nm, wherein the printing ink comprises a dynamic viscosity between 500 and 100 mPa/sec substantially at 25° C. and wherein the printing ink comprises a surface tension of at least 30 mN/m substantially at 25° C.
Further, for example document US 2009/0250828 A1 shows a method for manufacturing an ophthalmic lens comprising introducing a volume of photocurable lens material into a container, wherein said container comprises a mold surface. The method further comprises creating a digital 3D mathematical model defining corrective needs of an eye and projecting program patterns of UV light through said mold via a pattern generator, or in said program patterns of UV light cure set photocurable lens material into a lens shape defined by said mold surface and said digital model.
Further, document US 2012/0019936 A1 shows a device for directing light beams comprising a translucent substrate and a light directing structure in at least a portion of the substrate, wherein the light directing structure comprises a substantially transparent material which is arranged in a pattern on the substrate in such a way that the light directing structure comprises at least one optical prism. Further, for example document DE 10 2006 003 310 A1 shows a method for manufacturing a lenticular image and a method for producing braille or embossed printing. The method includes generating lenses by applying material in layers or by generating lenses via a multitude of subsequently applied material layers or portions.
Further, the document DE 10 2009 004 377 A1 shows a method for manufacturing a spectacle lens, a computer program product and the use of a spectacle lens manufacturing device. In particular, the method comprises the steps of providing a material processing device, providing build data of the spectacle lens at manufacturing the spectacle lens according to the provided build data by unit-wise positioning of at least one material via the material processing device.
Document DE 10 2009 004 380 A1 shows a similar approach for manufacturing an individual spectacle frame. Further, document DE 10 2009 004 379 A1 shows a similar method for manufacturing a spectacle lens blank mount.
Last, document WO 2013/149891 A1 shows an invention related to a device for producing customer-made spectacles comprising a scanning unit and producing unit, wherein the scanning unit is configured for scanning at least a part of customer's face and wherein the producing unit comprises at least a printing device for printing a spectacle lens and/or a spectacle frame, wherein the printing device is configured for printing the spectacle lens and/or the spectacle frame in dependency of scanning data of the scanning unit.
However, all these provided methods still consume a significant amount of time since the spectacle lenses are produced completely via a three-dimensional printing process. Further, currently, the raw material costs for three-dimensional printing processes amount up to 800 times the costs of conventional manufacturing techniques. Depending on the resolution of such printing processes, the time for producing two spectacle lenses for an individual wearer and the costs involved still hinder the application of such methods in the market.